1998-08-06 04:00:00 PDT MARIN COUNTY -- A boat belonging to a Visalia doctor who was attempting to sail from Richmond to Hawaii was found unmanned near Point Reyes in Marin County earlier this week, prompting a widespread Coast Guard search by air and sea.

No one was aboard the 25-foot sail boat when it was discovered Tuesday evening near Duxberry Reef between Point Bonita and Point Reyes.

The sails were still up and nothing was missing when it washed ashore. Two weeks' worth of food and provisions were found on board.

The boat's owner and skipper, 51-year-old William Groppe of Visalia, set sail from Richmond on Sunday for a solo vacation trip to Hawaii, Coast Guard officials said. He is described as an experienced sailor.

Dozens of men and women from the Coast Guard searched for Groppe yesterday, but found no sign of him.

A Coast Guard cargo plane, two helicopters and two motor lifeboats scanned the surface of the water west of Point Reyes, looking as far as 100 miles offshore.

"All indications lead us to believe he fell off," said Coast Guard Petty Officer Jeff Alger.

"But as to how and why, we have no idea."

The boat provided few clues for investigators.

A coastal resident noticed the deserted boat and called the Coast Guard shortly before 9 p.m. Tuesday. The small boat's sails appeared to be slightly ripped by the wind.

"It seemed to be beat up at sea a little bit," Alger said.

But there was no major damage, Alger said, that would indicate a collision with another vessel or a submerged rock.

Although the seas Tuesday evening were relatively calm, visibility was close to zero in the foggy waters, Alger said. It is not clear how much of a factor the poor visibility was on the incident, Alger said.

Groppe was last seen Sunday in Richmond, where he had lunch with a friend before sailing off, Alger said.

About 30 Coast Guard personnel were involved in yesterday's search, including the crew of a patrol boat that monitored the water the entire evening.